CINCINNATI, Ohio (REUTERS) - Democratic presidential candidate Hillary Clinton will campaign for the first time with populist United States Senator Elizabeth Warren in Ohio on Monday (June 27), in an early move to neutralise Republican Donald Trump's appeal in the bellwether state.

Sen Warren is a fiery critic of Wall Street and one of Mrs Clinton's potential vice-presidential picks. Ohio has backed every successful presidential nominee since 1964 and no Republican has won the White House without carrying Ohio.

Mrs Clinton's decision to campaign with Sen Warren for the first time in Cincinnati, a city on Ohio's south-western border with Kentucky and Indiana, is a bid to stop Mr Trump from gaining ground in the state by focusing on how Mrs Clinton would help improve the US economy.

"Ohio reflects the broader debate that's going on about economic uncertainty and the impact of free trade in particular," said Mr Jim Manley, a Democratic strategist supporting Clinton. "It's very clear that Donald Trump intends to make a major play for the industrial Midwest and so I think this highlights that she doesn't intend to let him get away with it."

Though Sen Warren is an influential progressive within the Democratic Party, strategists said her rhetoric about breaking up too-big-to-fail banks and reining in corporate excess resonates with two groups Mrs Clinton must court to win the Nov 8 election.

Supporters of former Clinton rival Bernie Sanders who backed the Democratic socialist US senator in the primary campaign and those anxious about the economy who are drawn to Mr Trump's promise to toss out international trade deals are both drawn to Sen Warren's platform, strategists said.

"Warren's appeal is not limited to liberals. It extends to people like many Trump supporters who feel the system only works for the rich and powerful," Democratic strategist Brad Bannon said.

"Because of that, Cincinnati is a good place to test Warren's appeal as a VP candidate who can attack Trump and win over some of his angry middle class supporters," he added.

Since becoming the presumptive Democratic nominee, former Secretary of State Clinton has tried to paint businessman Trump, the presumptive Republican nominee, as fundamentally unfit for the presidency.

Mrs Clinton's campaign in recent days has accused Mr Trump of caring more about how Britain's vote to leave the European Union would benefit him financially than how it would impact the US economy.

Mr Trump's campaign said the historic vote showed Mr Trump was in sync with a global sentiment of economic frustration and Mrs Clinton was out of step.

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